Compilare: user.cpp: In function ‘int main()’: user.cpp:55:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < ev.size(); i++) ^ user.cpp:40:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concert.in","r",stdin); ^ user.cpp:41:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("concert.out","w",stdout); ^ user.cpp:43:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp: In member function ‘void intr::read()’: user.cpp:23:58: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d", &a, &b, &win, &pay_a, &pay_b); ^